FORT LAUDERDALE, Fla. -- A Miami man is charged with using Facebook postings to threaten to harm or assassinate President Barack Obama during his visit to South Florida last week, according to a federal criminal complaint.

A Secret Service affidavit filed in Miami federal court identified the man as 20-year-old Joaquin Amador Serrapio Jr. of Miami.

According to the affidavit, Serrapio posted the threatening comments under the Facebook name "Jay Valor" during Obama's visit to the University of Miami last Thursday. There's no indication that Serrapio took any steps to carry out the threat or that the president was ever in any danger. The Secret Service did not immediately respond Tuesday to a telephone call seeking additional comment.

In the first posting on Feb. 21, Serrapio as "Jay Valor" allegedly said this: "Who wants to help me assassinate Obummer while hes at UM this week?"

Then on Thursday, the day of Obama's visit, the Secret Service affidavit said Serrapio made another posting.

"If anyones going to UM to see obama today, get ur phones out and record. Cause at any moment im gonna put a bullet through his head and u don't wanna miss that! Youtube!"

Later that day, Secret Service agents went to Serrapio's home, where he and his mother agreed to allow a search. The agents found an iPad showing the initial Facebook post about assassinating Obama. They also found a sniper-style pellet rifle and a pellet handgun in Serrapio's bedroom.

After his arrest, Serrapio admitted posting the threats, according to the affidavit. Serrapio's court-apppointed attorney declined comment Tuesday.

The agents also searched Serrapio's cell phone, which included a text message from someone pointing out that Serrapio could get into trouble for the Facebook postings.

"I know I can b killed by this communist administration and im challenging them," he texted back, according to the affidavit. "Let's see what those (expletives) got."

Serrapio was arrested the same day as Obama's visit and is now free on $70,000 bail, according to court records. He is scheduled to enter a plea at an arraignment set for March 9 and has been ordered to undergo a mental health assessment.

The charge of threatening to assassinate or inflict bodily harm on the president carries a maximum five-year prison sentence.

According to his Facebook page, Serrapio fronts the "J. Valor Band" rock group that specializes in classic rock covers.